As shown in FIG. 1, autonomous robots 1, each of which independently acts in accordance with an instruction from a user or a surrounding environment, have been developed. Regarding some of the robots, e.g., for the purpose of controlling a household electrical appliance 4-1 through a network 3 and receiving a command from a personal computer 4-2 over the network 3, each robot can communicate with an access point 2. The robot 1 communicates with the access point 2 by radio based on, e.g., IEEE (Institute of Electrical and Electronic Engineers) 802.11b (refer to Japanese Unexamined Patent Application Publication No. 2001-191279).
The typical robot 1 has an indicator indicating the strength of a radio signal. For example, when a device, such as a microwave oven, for emitting electromagnetic waves is running, or when the robot 1 is hidden by an object while the robot 1 is independently moving, a user can recognize a reduction in the quality of communication with the access point 2.
However, according to an approach using such an indicator, when the user pays attention to anything, e.g., if the user interacts with the robot 1, the user cannot sufficiently recognize the state of communication.